j0e1in · April 21, 2018 19:45
diff --git a/run_async_in_thread.py b/run_async_in_thread.py
 ##########################################################
 # Use cases
 #     1. Start an async function in __init__
 #     2. Start an endless (while loop) async function while current event loop is running
 #     3. ...
 # 
 # Limitations
 #     1. Some libraries (eg. motor) cannot be executed using this method, because you can't control how event loop is retrieved. (See another method below)
 #
 # Usage:
 #       async def func(count, add=1)
 #           while True:
 #               count += add
 #               print(count)
 #               await asyncio.sleep(1)
 #
 #       th = run_async_in_thread(func, 1, add=3)
 #
 #       # Tip: restart a thread if it is dead
 #       while True:
 #           if not th.is_alive():
 #               th = run_async_in_thread(func, 1, add=3)
 ##########################################################

 from threading import Thread
 import asyncio

 def run_async_in_thread(func, *args, **kwargs):

    def run_async(func, loop, *args, **kwargs):
        loop.run_until_complete(func(*args, **kwargs))

    loop = asyncio.new_event_loop()
    th = Thread(target=run_async, args=(func, loop, *args), kwargs=kwargs)
    th.start()

    return th


 # Another option is to use `asyncio.run_coroutine_threadsafe`.
 # This method is more robust to many situation, 
 # but it requires an additional step to get traceback.
 
 import asyncio
 import sys
 import traceback
    
 async def catch_traceback(fn, *args, **kwargs):
    """ Wraps `fn`(coroutine) in order to preserve the
        traceback of any kind of exception.
    """
    try:
        return await fn(*args, **kwargs)
    except Exception:
        raise sys.exc_info()[0](traceback.format_exc())

 loop = asyncio.get_event_loop()
 future = asyncio.run_coroutine_threadsafe(
    catch_traceback(func, 1, add=3), loop)
 
 while True:
    try:
        res = future.exception(timeout=1) # try to retrive exception / result
    except concurrent.futures.TimeoutError:
        pass # skip and do other tasks first
    else:
       # handle exception / result
	##########################################################
	# Use cases
	# 1. Start an async function in __init__
	# 2. Start an endless (while loop) async function while current event loop is running
	# 3. ...
	#
	# Limitations
	# 1. Some libraries (eg. motor) cannot be executed using this method, because you can't control how event loop is retrieved. (See another method below)
	#
	# Usage:
	# async def func(count, add=1)
	# while True:
	# count += add
	# print(count)
	# await asyncio.sleep(1)
	#
	# th = run_async_in_thread(func, 1, add=3)
	#
	# # Tip: restart a thread if it is dead
	# while True:
	# if not th.is_alive():
	# th = run_async_in_thread(func, 1, add=3)
	##########################################################

	from threading import Thread
	import asyncio

	def run_async_in_thread(func, args, *kwargs):

	def run_async(func, loop, args, *kwargs):
	loop.run_until_complete(func(args, *kwargs))

	loop = asyncio.new_event_loop()
	th = Thread(target=run_async, args=(func, loop, *args), kwargs=kwargs)
	th.start()

	return th


	# Another option is to use `asyncio.run_coroutine_threadsafe`.
	# This method is more robust to many situation,
	# but it requires an additional step to get traceback.

	import asyncio
	import sys
	import traceback

	async def catch_traceback(fn, args, *kwargs):
	""" Wraps `fn`(coroutine) in order to preserve the
	traceback of any kind of exception.
	"""
	try:
	return await fn(args, *kwargs)
	except Exception:
	raise sys.exc_info()[0](traceback.format_exc())

	loop = asyncio.get_event_loop()
	future = asyncio.run_coroutine_threadsafe(
	catch_traceback(func, 1, add=3), loop)

	while True:
	try:
	res = future.exception(timeout=1) # try to retrive exception / result
	except concurrent.futures.TimeoutError:
	pass # skip and do other tasks first
	else:
	# handle exception / result